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        Using Stored Collections
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          <th width="60%" align="center">Appendix 1. 
        API Notes and Details
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    <div class="sect1" lang="en" xml:lang="en">
      <div class="titlepage">
        <div>
          <div>
            <h2 class="title" style="clear: both"><a id="UsingStoredCollections"></a>
        Using Stored Collections
    </h2>
          </div>
        </div>
      </div>
      <div class="toc">
        <dl>
          <dt>
            <span class="sect2">
              <a href="UsingStoredCollections.html#StoredCollectionAccessMethods">
            Stored Collection and Access Methods
        </a>
            </span>
          </dt>
          <dt>
            <span class="sect2">
              <a href="UsingStoredCollections.html#StoredVersusStandardCollections">
            Stored Collections Versus Standard Java Collections
        </a>
            </span>
          </dt>
          <dt>
            <span class="sect2">
              <a href="UsingStoredCollections.html#StoredCollectionCharacteristics">
            Other Stored Collection Characteristics
        </a>
            </span>
          </dt>
          <dt>
            <span class="sect2">
              <a href="UsingStoredCollections.html#WhyJavaCollections">
            Why Java Collections for Berkeley DB
        </a>
            </span>
          </dt>
        </dl>
      </div>
      <p>
        When a stored collection is created it is based on either a
    
    <a class="ulink" href="../../java/com/sleepycat/db/Database.html" target="_top">Database</a>
    
    or a 
    
    <span>
        <a class="ulink" href="../../java/com/sleepycat/db/SecondaryDatabase.html" target="_top">SecondaryDatabase</a>.
    </span>
    When a database is used, the primary key of the database is used as
    the collection key. When a secondary database is used, the index
    key is used as the collection key. Indexed collections can be used
    for reading elements and removing elements but not for adding or
    updating elements.
    </p>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="StoredCollectionAccessMethods"></a>
            Stored Collection and Access Methods
        </h3>
            </div>
          </div>
        </div>
        <p>
        The use of stored collections is constrained in certain respects as
        described below.
        <span>
            Most of these restrictions have to do with 
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/List.html" target="_top">List</a>
                
            interfaces; for 
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.html" target="_top">Map</a>
                
            interfaces, most all access modes are fully supported since the
            Berkeley DB model is map-like.
        </span>
    </p>
        <div class="itemizedlist">
          <ul type="disc">
            <li>
              <p>
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/SortedSet.html" target="_top">SortedSet</a>
                 
                and 
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/SortedMap.html" target="_top">SortedMap</a>
                

                interfaces may only be used if keys are ordered. This means ordered keys are required for creating a

                <a class="ulink" href="../../java/com/sleepycat/collections/StoredSortedEntrySet.html" target="_top">StoredSortedEntrySet</a>, 
                <a class="ulink" href="../../java/com/sleepycat/collections/StoredSortedKeySet.html" target="_top">StoredSortedKeySet</a>, 
                <a class="ulink" href="../../java/com/sleepycat/collections/StoredSortedMap.html" target="_top">StoredSortedMap</a>, or
                <a class="ulink" href="../../java/com/sleepycat/collections/StoredSortedValueSet.html" target="_top">StoredSortedValueSet</a>.
            </p>
            </li>
            <li>
              <p>
                All iterators for stored collections implement the
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html" target="_top">ListIterator</a>
                
                interface as well as the
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Iterator.html" target="_top">Iterator</a>
                
                interface.
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html#hasPrevious()" target="_top">ListIterator.hasPrevious()</a>
                
                and
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html#previous()" target="_top">ListIterator.previous()</a>
                
                work in all cases.
                <span>
                    However, the following 
                        <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html" target="_top">ListIterator</a>
                        
                    method behavior is dependent on the access method.
                </span>
            </p>
              <div class="itemizedlist">
                <ul type="circle">
                  <li>
                    <p>
                        <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html#nextIndex()" target="_top">ListIterator.nextIndex()</a>
                        
                       and 
                        <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html#previousIndex()" target="_top">ListIterator.previousIndex()</a>
                        
                       only work when record number keys are used, and throw
                        <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/UnsupportedOperationException.html" target="_top">UnsupportedOperationException</a>
                        
                       otherwise.
                    </p>
                  </li>
                  <li>
                    <p>
                        <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html#add()" target="_top">ListIterator.add()</a>
                        
                        inserts before the current position and renumbers following keys if the RECNO-RENUMBER
                        access method is used.
                    </p>
                  </li>
                  <li>
                    <p>
                         For all access methods other than RECNO-RENUMBER:
                    </p>
                    <div class="itemizedlist">
                      <ul type="square">
                        <li>
                          <p>
                                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html#add()" target="_top">ListIterator.add()</a>
                                
                                throws
                                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/UnsupportedOperationException.html" target="_top">UnsupportedOperationException</a>
                                
                                if duplicates are not allowed.
                            </p>
                        </li>
                        <li>
                          <p>
                                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html#add()" target="_top">ListIterator.add()</a>
                                
                                inserts a duplicate before the current position
                                if duplicates are unsorted.
                            </p>
                        </li>
                        <li>
                          <p>
                                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html#add()" target="_top">ListIterator.add()</a>
                                
                                inserts a duplicate in sorted order if
                                duplicates are sorted.
                            </p>
                        </li>
                      </ul>
                    </div>
                  </li>
                  <li>
                    <p>
                        <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html#set()" target="_top">ListIterator.set()</a>
                        
                    throws
                    <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/UnsupportedOperationException.html" target="_top">UnsupportedOperationException</a>
                    
                    if sorted duplicates are configured, since updating with sorted duplicates would change the
                    iterator position.
                </p>
                  </li>
                </ul>
              </div>
            </li>
            <li>
              <p>
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.Entry.html#setValue()" target="_top">Map.Entry.setValue()</a>
                
                throws
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/UnsupportedOperationException.html" target="_top">UnsupportedOperationException</a>
                
                if duplicates are sorted.
            </p>
            </li>
            <li>
              <p>
                Only the access methods that use a record number key may be used
                with a 
                    <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/List.html" target="_top">List</a>
                    <code class="classname">List</code>
                view.
            </p>
            </li>
            <li>
              <p>
                To create a stored List that supports the 
                    <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/List.html#add()" target="_top">List.add()</a> 
                    <code class="methodname">List.add()</code> 
                method, only the RECNO-RENUMBER access method may be used.
            </p>
            </li>
            <li>
              <p>
                For List access methods that do not support 
                    <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/List.html#add()" target="_top">List.add()</a> 
                    <code class="methodname">List.add()</code> 
                (RECNO, QUEUE, and BTREE-RECNUM):
            </p>
              <div class="itemizedlist">
                <ul type="circle">
                  <li>
                    <p>
                        <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/List.html#add()" target="_top">List.add()</a> 
                        <code class="methodname">List.add()</code> 
                       and 
                        <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html#add()" target="_top">ListIterator.add()</a> 
                        <code class="methodname">ListIterator.add()</code> 
                       always throw
                        <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/UnsupportedOperationException.html" target="_top">UnsupportedOperationException</a> .
                    </p>
                  </li>
                  <li>
                    <p>
                        <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/List.html#remove()" target="_top">List.remove()</a> 
                        <code class="methodname">List.remove()</code> 
                       and 
                        <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html#remove()" target="_top">ListIterator.remove()</a> 
                        <code class="methodname">ListIterator.remove()</code> 
                       do not cause list indices to be renumbered. However, iterators will skip
                       the removed values.
                    </p>
                  </li>
                </ul>
              </div>
              <p>
                For these access methods, stored Lists are most useful as
                read-only collections where indices are not required to be
                sequential.
            </p>
            </li>
            <li>
              <p>
                When duplicates are allowed the
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Collection.html" target="_top">Collection</a>
                
                interfaces are modified in several ways as described in the next
                section.
            </p>
            </li>
          </ul>
        </div>
      </div>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="StoredVersusStandardCollections"></a>
            Stored Collections Versus Standard Java Collections
        </h3>
            </div>
          </div>
        </div>
        <p>
        Stored collections have the following differences with the
        standard Java collection interfaces. Some of these are interface
        contract violations.
    </p>
        <p>
        The Java collections interface does not support duplicate keys
        (multi-maps or multi-sets). When the access method allows duplicate
        keys, the collection interfaces are defined as follows.
    </p>
        <div class="itemizedlist">
          <ul type="disc">
            <li>
              <p>
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.html#entrySet()" target="_top">Map.entrySet()</a>
                
                may contain multiple
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.Entry.html" target="_top">Map.Entry</a>
                
                objects with the same key.
            </p>
            </li>
            <li>
              <p>
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.html#keySet()" target="_top">Map.keySet()</a>
                
                always contains unique keys, it does not contain duplicates.
            </p>
            </li>
            <li>
              <p>
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.html#values()" target="_top">Map.values()</a>
                
                contains all values including the values
                associated with duplicate keys.
            </p>
            </li>
            <li>
              <p>
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.html#put()" target="_top">Map.put()</a>
                
                appends a duplicate if the key already exists rather than replacing
                the existing value, and always returns null.
            </p>
            </li>
            <li>
              <p>
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.html#remove()" target="_top">Map.remove()</a>
                
                removes all duplicates for the specified key.
            </p>
            </li>
            <li>
              <p>
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.html#get()" target="_top">Map.get()</a>
                
                returns the first duplicate for the specified key.
            </p>
            </li>
            <li>
              <p>
                <a class="ulink" href="../../java/com/sleepycat/collections/StoredMap.html#duplicates(java.lang.Object)" target="_top">StoredMap.duplicates()</a>
                
                is an additional method for returning the values for a given key as a
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Collection.html" target="_top">Collection</a>.
            </p>
            </li>
          </ul>
        </div>
        <p>
        Other differences are:
    </p>
        <div class="itemizedlist">
          <ul type="disc">
            <li>
              <p>
                Collection.size() and Map.size() always throws
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/UnsupportedOperationException.html" target="_top">UnsupportedOperationException</a>.
                This is because the number of
                records in a database cannot be determined reliably or
                cheaply.
            </p>
            </li>
            <li>
              <p>
                Because the size() method cannot be used, the bulk operation
                methods of standard Java collections cannot be passed stored
                collections as parameters, since the implementations rely on
                size(). However, the bulk operation methods of stored collections
                can be passed standard Java collections as parameters.
                <code class="literal">storedCollection.addAll(standardCollection)</code> is allowed
                while <code class="literal">standardCollection.addAll(storedCollection)</code> is
                <span class="emphasis"><em>not</em></span> allowed. This restriction applies to the standard
                collection constructors that take a Collection parameter (copy
                constructors), the Map.putAll() method, and the following
                Collection methods: addAll(), containsAll(), removeAll() and
                retainAll().
            </p>
            </li>
            <li>
              <p>
                The <code class="methodname">ListIterator.nextIndex()</code> method
                returns <code class="literal">Integer.MAX_VALUE</code>
                for stored lists when positioned at the end of the list, rather
                than returning the list size as specified by the ListIterator
                interface. Again, this is because the database size is not
                available.
            </p>
            </li>
            <li>
              <p>
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Comparator.html" target="_top">Comparator</a>
                
                objects cannot be used and the
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/SortedMap.html#comparator()" target="_top">SortedMap.comparator()</a>
                
                and
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/SortedSet.html#comparator()" target="_top">SortedSet.comparator()</a>
                
                methods always return null. The
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Comparable.html" target="_top">Comparable</a>
                
                interface is not supported. However, Comparators that operate on
                byte arrays may be specified using
                
                <span>
                    <a class="ulink" href="../../java/com/sleepycat/db/DatabaseConfig.html#setBtreeComparator(java.util.Comparator)" target="_top">DatabaseConfig.setBtreeComparator</a>.
                </span>
            </p>
            </li>
            <li>
              <p>
                The
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html#equals()" target="_top">Object.equals()</a>
                
                method is not used to determine whether a key
                or value is contained in a collection, to locate a value by key,
                etc. Instead the byte array representation of the keys and values
                are used. However, the equals() method <span class="emphasis"><em>is</em></span> called for each
                key and value when comparing two collections for equality. It is
                the responsibility of the application to make sure that the
                equals() method returns true if and only if the byte array
                representations of the two objects are equal. Normally this occurs
                naturally since the byte array representation is derived from the
                object's fields.
            </p>
            </li>
          </ul>
        </div>
      </div>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="StoredCollectionCharacteristics"></a>
            Other Stored Collection Characteristics
        </h3>
            </div>
          </div>
        </div>
        <p>
        The following characteristics of stored collections are
        extensions of the definitions in the 
        <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/package-summary.html" target="_top">java.util</a>
        
        package. These differences do not violate the Java
        collections interface contract.
    </p>
        <div class="itemizedlist">
          <ul type="disc">
            <li>
              <p>
                All stored collections are thread safe (can be used by multiple
                threads concurrently) 
                    <span>
                        whenever the Berkeley DB Concurrent Data Store or
                        Transactional Data Store environment is used.
                    </span>
                Locking is handled by the Berkeley DB
                environment. To access a collection from multiple threads, creation
                of synchronized collections using the
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Collections.html" target="_top">Collections</a>
                
                class is not necessary 
                    <span>
                        except when using the Data Store environment.
                    </span>
                Iterators, however, should always be used only by a single thread.
            </p>
            </li>
            <li>
              <p>
                All stored collections may be read-only if desired by passing
                false for the writeAllowed parameter of their constructor. Creation
                of immutable collections using the
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Collections.html" target="_top">Collections</a>
                
                class is not necessary.
            </p>
            </li>
            <li>
              <p>
                A stored collection is partially read-only if a secondary
                index is used. Specifically, values may be removed but may not be
                added or updated. The following methods will throw
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/UnsupportedOperationException.html" target="_top">UnsupportedOperationException</a>
                
                when an index is used:
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Collection.html#add()" target="_top">Collection.add()</a>,
                <span><a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/List.html#set()" target="_top">List.set()</a>,</span>
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html#set()" target="_top">ListIterator.set()</a>
                
                and
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.Entry.html#setValue()" target="_top">Map.Entry.setValue()</a>.
            </p>
            </li>
            <li>
              <p>
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/SortedMap.html#entrySet()" target="_top">SortedMap.entrySet()</a>
                
                and
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/SortedMap.html#keySet()" target="_top">SortedMap.keySet()</a>
                
                return a
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/SortedSet.html" target="_top">SortedSet</a>,
                not just a
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Set.html" target="_top">Set</a>
                
                as specified in Java collections interface. This allows using the
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/SortedSet.html" target="_top">SortedSet</a>
                
                methods on the returned collection.
            </p>
            </li>
            <li>
              <p>
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/SortedMap.html#values()" target="_top">SortedMap.values()</a>
                
                returns a
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/SortedSet.html" target="_top">SortedSet</a>,
                not just a
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Collection.html" target="_top">Collection</a>,
                whenever the keys of the map can be derived from the values using
                an entity binding. Note that the sorted set returned is not really
                a set if duplicates are allowed, since it is technically a
                collection; however, the
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/SortedSet.html" target="_top">SortedSet</a>
                
                methods (for example, subSet()), can still be used.
            </p>
            </li>
            <li>
              <p>
                For
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/SortedSet.html" target="_top">SortedSet</a>
                
                and
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/SortedMap.html" target="_top">SortedMap</a>
                
                views, additional subSet() and subMap() methods are provided that
                allow control over whether keys are treated as inclusive or
                exclusive values in the key range.
            </p>
            </li>
            <li>
              <p>
                Keys and values are stored by value, not by reference. This is
                because objects that are added to collections are converted to byte
                arrays (by bindings) and stored in the database. When they are
                retrieved from the collection they are read from the database and
                converted from byte arrays to objects. Therefore, the object
                reference added to a collection will not be the same as the
                reference later retrieved from the collection.
            </p>
            </li>
            <li>
              <p>
                A runtime exception,
                <a class="ulink" href="../../java/com/sleepycat/util/RuntimeExceptionWrapper.html" target="_top">RuntimeExceptionWrapper</a>,
                is thrown whenever database exceptions occur which are not runtime
                exceptions. The
                <a class="ulink" href="../../java/com/sleepycat/util/RuntimeExceptionWrapper.html#getCause()" target="_top">RuntimeExceptionWrapper.getCause()</a>
                
                method can be called to get the underlying exception.
            </p>
            </li>
            <li>
              <p>
                All iterators for stored collections implement the
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html" target="_top">ListIterator</a>
                
                interface as well as the
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Iterator.html" target="_top">Iterator</a>
                
                interface. This is to allow use of the
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html#hasPrevious()" target="_top">ListIterator.hasPrevious()</a>
                
                and
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html#previous()" target="_top">ListIterator.previous()</a>
                
                methods, which work for all collections
                since Berkeley DB provides bidirectional cursors.
            </p>
            </li>
            <li>
              <p>
                All stored collections have a
                <a class="ulink" href="../../java/com/sleepycat/collections/StoredCollection.html#iterator(boolean)" target="_top">StoredCollection.iterator(boolean)</a>
                
                method that allows creating
                a read-only iterator for a writable collection. For the standard
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Collection.html#iterator()" target="_top">Collection.iterator()</a>
                
                method, the iterator is read-only only
                when the collection is read-only. 
                
                <span>Read-only iterators are important
                for using the Berkeley DB Concurrent Data Store environment, since
                only one write cursors may be open at one time.</span>
            </p>
            </li>
            <li>
              <p>
                Iterator stability for stored collections is greater than the
                iterator stability defined by the Java collections interfaces.
                Stored iterator stability is the same as the cursor stability
                defined by Berkeley DB.
            </p>
            </li>
            <li>
              <p>
                When an entity binding is used, updating (setting) a value is
                not allowed if the key in the entity is not equal to the original
                key. For example, calling
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.html#put()" target="_top">Map.put()</a>
                
                is not allowed when the key parameter is not equal to the key of
                the entity parameter.
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.html#put()" target="_top">Map.put()</a>,
                <span><a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/List.html#set()" target="_top">List.set()</a>,</span>
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html#set()" target="_top">ListIterator.set()</a>,
                and
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Map.Entry.html#setValue()" target="_top">Map.Entry.setValue()</a>
                
                will throw
                <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/IllegalArgumentException.html" target="_top">IllegalArgumentException</a>
                
                in this situation.
            </p>
            </li>
            <li>
              <p>
                Adding and removing items from stored lists is not allowed for
                sublists. This is simply an unimplemented feature and may be
                changed in the future. Currently for sublists the following
                methods throw 
                        <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/UnsupportedOperationException.html" target="_top">UnsupportedOperationException</a>:
                    <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/List.html#add()" target="_top">List.add()</a><code class="methodname">List.add()</code>,
                        <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/List.html#remove()" target="_top">List.remove()</a><code class="methodname">List.remove()</code>, 
                        <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html#add()" target="_top">ListIterator.add()</a>
                        
                and 
                        <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/ListIterator.html#remove()" target="_top">ListIterator.remove()</a><code class="methodname">ListIterator.remove()</code>. 
            </p>
            </li>
            <li>
              <p>
                The

                <span>
                    <a class="ulink" href="../../java/com/sleepycat/collections/StoredList.html#append(java.lang.Object)" target="_top">StoredList.append(java.lang.Object)</a>
                    
                    and
                </span>

                <a class="ulink" href="../../java/com/sleepycat/collections/StoredMap.html#append(java.lang.Object)" target="_top">StoredMap.append(java.lang.Object)</a>
                
                extension method<span>s</span> allows
                adding a new record with an automatically assigned key. 
                <span>
                    Record number assignment by the database itself is supported
                    for QUEUE, RECNO and RECNO-RENUMBER databases.
                </span>
                An application-defined
                <a class="ulink" href="../../java/com/sleepycat/collections/PrimaryKeyAssigner.html" target="_top">PrimaryKeyAssigner</a>
                
                is used to assign the key value.
            </p>
            </li>
          </ul>
        </div>
      </div>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="WhyJavaCollections"></a>
            Why Java Collections for Berkeley DB
        </h3>
            </div>
          </div>
        </div>
        <p>
        The Java collections interface was chosen as the best Java API
        for DB given these requirements:
    </p>
        <div class="orderedlist">
          <ol type="1">
            <li>
              <p>
                Provide the Java developer with an API that is as familiar and
                easy to use as possible.
            </p>
            </li>
            <li>
              <p>
                Provide access to all, or a large majority, of the features of
                the underlying Berkeley DB storage system.
            </p>
            </li>
            <li>
              <p>
                Compared to the DB API, provide a higher-level API
                that is oriented toward Java developers.
            </p>
            </li>
            <li>
              <p>
                For ease of use, support object-to-data bindings, per-thread
                transactions, and some traditional database features such as
                foreign keys.
            </p>
            </li>
            <li>
              <p>
                Provide a thin layer that can be thoroughly tested and which
                does not significantly impact the reliability and performance of
                DB.
            </p>
            </li>
          </ol>
        </div>
        <p>
        Admittedly there are several things about the Java Collections
        API that don't quite fit with DB or with any transactional
        database, and therefore there are some new rules for applying the
        Java Collections API. However, these disadvantages are considered
        to be smaller than the disadvantages of the alternatives:
    </p>
        <div class="itemizedlist">
          <ul type="disc">
            <li>
              <p>
                A new API not based on the Java Collections API could have been
                designed that maps well to DB but is higher-level.
                However, this would require designing an entirely new model. The
                exceptions for using the Java Collections API are considered easier
                to learn than a whole new model. A new model would also require a
                long design stabilization period before being as complete and
                understandable as either the Java Collections API or the DB
                API.
            </p>
            </li>
            <li>
              <p>
                The ODMG API or another object persistence API could have been
                implemented on top of DB. However, an object persistence
                implementation would add much code and require a long stabilization
                period. And while it may work well for applications that require
                object persistence, it would probably never perform well enough for
                many other applications.
            </p>
            </li>
          </ul>
        </div>
      </div>
    </div>
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